1. Field of the Invention
The present invention relates to an ophthalmologic apparatus capable of conducting at least subjective measurement of the refractive power of an eye to be examined.
2. Description of the Related Art
Up to now, with respect to measurement of the refractive power of an eye to be examined (ocular refractive power), a subjective eye examination for conducting measurement based on responses of a person to be examined to various indexes such as Landolt rings and an objective eye examination which is conducted without using the responses of the person to be examined are used in combination. Now, an ophthalmologic apparatus capable of effectively using both the subjective eye examination and the objective eye examination become widely available. Therefore, attempts of improvement in efficiency and reliability of the examination, size reduction of the apparatus etc. are conducted.
Also, in order to further improve the efficiency of the examination, an ophthalmologic apparatus in which the person to be examined him/herself can conduct eye examination has been developed. As such an ophthalmologic apparatus, an ophthalmologic apparatus described in, for example, JP 2002-119471 A (specification paragraph [0026] and FIG. 3) has been known. The ophthalmologic apparatus described in JP 2002-119471 A can conduct both the subjective eye examination and the objective eye examination. A moving image and a still image which show an measurement order are displayed on a monitor device under the control of a computer and the measurement order is also announced, so that the person to be examined can be automatically guided.
It is greatly expected that the automated ophthalmologic apparatus become widely available in the future. It is a fact that a problem to be solved to achieve the wide use remains. For example, when a plurality of indexes or a plurality of index indicating states (states of index images projected to the eye to be examined) are made to appear in the eye to be examined and an examination is performed based on a result in which the person to be examined conducts subjective comparison and determination with respect to the visibility of the plurality of indexes and the like, it is difficult for the person to be examined to distinguish an index, which actually appears in the eye, among from the plurality of indexes and the like. An example thereof is given. In a cross cylinder test (hereinafter referred to as a CC test) which is a general method of an astigmatic examination, an examination is performed based on a result in which the person to be examined conducts comparison and determination as to clearly recognize which of a pair of index indicating states produced by reversing positive and negative refractive powers of the cross cylinder. In this time, the person to be examined becomes confused by not being able to distinguish which is the index indicating state for the power produced in many cases. Therefore, this causes that a time period required for the eye examination is lengthened and becomes a factor that the reliability of the eye examination is deteriorated.
Also, even in the case of the CC test which is conducted in the presence of an examiner and/or an assistant, it is difficult for the person to be examined to smoothly select among the index indicating states as in the above-mentioned case.
Note that, there has been known an ophthalmologic apparatus in which identification information visually identifiable is provided to each of a pair of cylindrical lenses used for the CC test and a pair of operational direction indexes corresponding to the identification information are provided to an astigmatic power switching operating unit for conducting astigmatic power switching and an astigmatic axis operating unit for conducting astigmatic axis switching, which are operated by the examiner, so that the astigmatic power switching operating unit and the astigmatic axis operating unit can be operated toward the operational direction index corresponding to any one of the identification information recognized by the person to be examined (see JP 2992337 B (claims)). According to this ophthalmologic apparatus, the response of the person to be examined to the identification information directly becomes to mean the operational direction index of the astigmatic axis operating unit or the astigmatic power switching operating unit. Therefore, the examiner can accurately and speedily conduct astigmatic examination.
But, the identification information only contributes to improvement in operationality of the apparatus operated by the examiner, and a labor and a cost are required for providing the identification information to each of a large number of cylindrical lenses.